Conference Highlights: ASTRO 2018

New research was presented at ASTRO 2018, the American Society for Radiation Oncology annual meeting, from October 21 to 24 in San Antonio. The features below highlight some of the studies that emerged from the conference.

Liquid Biopsy in HPV Oropharyngeal Cancer

Despite liquid biopsies generating strong interest among pathologists and oncologists, an expert panel recently reported that such assays are not yet ready for everyday use in diagnosing or managing early-stage or advanced solid tumors. Whether circulating tumor human papillomavirus DNA (ctHPVDNA) can be an effective method of surveillance for patients with p16-positive oropharyngeal squamous cell carcinoma (OPSCC) remained to be seen until researchers recently developed a highly specific, sensitive liquid biopsy blood test for patients with HPV-associated OPSCC. Among patients whose cane had metastasized at baseline, blood specimens were collected at baseline, weekly during treatment, and with each follow-up visit for extraction of plasma circulating nucleic acid. The sensitivity of ctHPVDNA testing was 100%, the specificity was 90%, the negative predictive value was 100%, and the positive predictive value was 50%.

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Hippocampus-Sparing Radiation for Brain Metastases

Prior research indicates that cognitive impairment affects more than 50% of patients who receive radiation to the brain, and 20% of cancer patients overall. Avoiding the hippocampus during whole-brain radiotherapy (WBRT) has been hypothesized to possibly help preserve cognitive function in cancer patients with brain metastases. To test this hypothesis, patients treated with hippocampus-sparing WBRT plus memantine were compared with controls who received WBRT plus memantine. Of those in the hippocampus-sparing group, 59.5% had cognitive failure function at 6 months, compared with 68.2% of controls. The study authors explained that the combined benefit of memantine plus hippocampal avoidance was a 425 relative risk reduction of cognitive impairment for cancer patients with brain involvement compared with WBRT alone.

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Radiation Therapy Outcomes & Race

Previous study results indicating that black race is an independent prognostic factor for poor outcomes among men with prostate cancer have led to the commonly held assumption that black men tend to have more aggressive disease that leads to lower survival rates when compared with white men. However, this assumption many not be true according to an investigation of the interplay of androgen-receptor (AR) activity and radiotherapeutic sensitivity that sought to provide a molecular rationale behind this disparity in outcomes. The investigators found that tumors from black men had lower AR activity and DNA-repair expression. Low AR activity was an independent predictor of distant metastasis, an association that remained even after adjusting for various characteristics. The tumors of black men also had decreased expression of the double-strand DNA repair pathway, increased expression of immune pathways, and increased radiosensitivity as predicted by a 24-gene prostate cancer radiation sensitivity score that was developed by the study team, who explain that this increase in radiotherapeutic sensitivity suggests that black men with prostate cancer will achieve better outcomes with radiation therapy than white men.

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Surgery, Radiation & Survival in Oligometastatic NSCLC

An earlier study found that lung consolidative therapy (LCT) can improve progression-free survival in patients with oligometastatic non-small cell lung cancer (NSCLC) after completing frontline systemic therapy without progression. However, with a short-term follow up, overall survival data from the study were not mature to be reported. Results presented at ASTRO 2018 now include updated data on progression-free survival as well as overall survival and toxicity date for 38.8 months of follow-up. All patients had stage IV NSCLC with three or fewer metastatic lesions who were randomized to maintenance therapy/observation (MT/O) or LCT, defined as radiation or surgery, to all remaining active sites of disease. Patients in the LCT had a median overall survival rate of 41.2 months, compared with 17.0 months for the MT/O group. Progression-free survival rates were 14.2 months for the LCT group and 4.4 months for the MT/O group. Median survival after progression was 37.6 months in the LCT group, compared with 9.4 months in the MT/O group.

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Survival Predictions & Intense EOL Care

Studies have shown that increased and intensive cancer treatment at the end of life (EOL) is associated with decreased quality of life and increased costs and often contradicts patients’ wishes. Despite guidelines defining intensive, poor-quality EOL cancer care, evidence suggests that cancer patients continue to receive poor-quality EOL care. For a study, researchers analyzed data on 375 patients with metastatic lung cancer for whom there were 468 care-provider encounters involving survival estimates. While oncologists accurately predicted survival (<12 months) in 77.7% of encounters, 32% of patients met at least one metric of poor-quality EOL care. When compared with patients whose survival predictions were accurate, those who were predicted to live for at least 24 months were 2.5 times more likely to meet at least one metric for intense EOL care. Those who were predicted to survive 18 to 24 months longer than they did were 39% more likely to have met at least one metric prior to death.